Answer : A (class Laptop implements Comparable <Laptop>)

Explanation :

Option B is incorrect because its usage will generate the following compilation error message:

>>>>
Laptop is not abstract and does not override abstract method compareTo(java.lang.Object) in java.lang.Comparable class Laptop implements Comparable {
>>>>

Option C and D are incorrect because the Interface Comparator defines the method 'compare', not 'compareTo'.